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Ingo andshōgi, ajōseki orjouseki (kanji characters定石 for go,定跡 forshōgi) is the studied sequences of moves for which the result is consideredbalanced for both black and white sides.
Ingo, because games typicallystart with plays in the corners,gojōseki are usually about corner play as the players try to gain local advantages there in order to obtain a better overall position. Though less common, there are alsojōseki for the middle game. InJapanese,jō (定) means "fixed" or "set" andseki (石) means stones, giving the literal meaning "set stones", as in "set pattern". InChinese, the term for joseki isdìngshì (定式).
The concept of "balance", here, often refers to an equitable trade-off between securing territory in the corner versus making goodthickness toward the sides and the center. In application, these concepts are very dynamic, and, often, deviations from ajōseki depend upon the needs of the situation and the available opportunities. While learningjōseki is a tool to defend against a local loss, players always seek to take advantage of weaknesses in the opponent'sshapes, often deviating from thejōseki.
Jōseki are not fixed but comprise patterns that have gained acceptance in professional games; they constitute a consensus that may change with certain caveats. Hence, the basic definition may be misleading for new players in that ajōseki can be misconstrued as foolproof and unalterable and as optimal for all situations. Manyjōseki are in fact useful only for study within an artificially confined corner,[1] and in real play are only considered good form when used in proper combination with other plays on the board (i.e. otherjōseki andfuseki moves).
Knowing a particularjōseki simply means that one knows a sequence of moves, resulting in a balance or fair trade-off between black and white positions. This is in practice much easier than appraising howjōseki relate to the rest of the board – hence,knowledge of jōseki is regarded as shallow, when compared with the ability to integrate a strategy into a complex game landscape.
Onego proverb states that "learningjōseki loses two stones in strength," which means that therote learning of sequences is not advantageous; rather, learningfrom ajōseki should be a player's goal.[2] Hence, the study ofjōseki is regarded as a double-edged sword and useful only if learned by understanding the principles behind each move, instead of by rote. Everyjōseki should be used as a specific tool that leaves the board in a particular shape.
Just as using an improper tool in machinery can be devastating, choosing the wrongjōseki can easily be worse than improvising one's own moves. In his bookA Way of Play for the 21st Century,Go Seigen compared choosing the properjōseki to choosing the proper medicine: "Pick the right one, and you feel better. Pick the wrong one, and you die." [par.]Rui Naiwei similarly remarked that "playingjoseki is easy [but] choosing the right one [in a game] is hard." [par.]
Ajōseki may fall out of use for various reasons, some of which may often seem minor to the amateur player; professionals may consider one variation suboptimal for a very specific reason – one which strong amateurs are not likely to exploit. There is no definitive guide to what is ajōseki; the situation withjōseki dictionaries is similar to that of natural language dictionaries: some entries are obsolete, and the list is likely to be incomplete.
Cornerjōseki conventionally start with one player occupying a corner point, in an empty 19×19 area of the board, and the other player replying with anapproach move (Japanese:kakari). The initial play in the corner is almost always on a 3-3, 3-4, 3-5, 4-4 or 4-5 point. Other plays that have been experimented with include 5-5, 6-3 and 6-4, all of which sacrifice territory for influence.
Of those plays, the classical 3-4 point (komoku) and more contemporary 4-4 point (hoshi) are the most used. The standard approaches are at 5-3 or 5-4 to the 3-4 point, and at 3-6/6-3 to the 4-4 point. The number of subsequent variations is then quite large (of the order of ten reasonable plays for the next one). Recently, some 3-3 invasion josekis became popular after it was used successfully by theAlphaGo series of models, such as theflying knife joseki.[3]
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| A Go game opening with two commonjōseki in the upper-right and lower-left. |
Breaking away from a sequence to play elsewhere (tenuki) before the conventional endpoint of thejōseki is not uncommon in higher level play. There is no formal theory for follow-up plays afterjōseki, though numerous set sequences can be seen in professional play.
It is imperative that players should not play ajōseki merely from rote memorization but adapt according to the overall board situation. It is important to keep in mind that go is a game involvingmarginal analysis andjōseki are merelyheuristics of sound play. Playingjōseki blindly will not improve one's game.[citation needed]
Inshogi, typically thebeginning of the games (序盤joban) consists of a number of relatively fixed series of moves for both players. This standard sequence of moves or ajōseki (spelled 定跡, unlike ingo where they are spelled定石) refers to especially recommended sequences of moves for a givenopening that lead to a balanced play for both sides. These sequences of moves are considered to be the best for a particular opening from the start of the game to the start of a full-scale battle, and are often recommended to amateur players to be able to master basic strategy.[4] Jōsekis are typically developed byprofessional players as a result of their individual research and actual games.[5] Jōsekis change continuously, some even becoming obsolete when they are reevaluated to no longer end up in a balanced play.
Examples of jōsekis in shogi include theSaginomiya joseki, theKimura joseki, and theYamada joseki.
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